Bacterial infections which on account of a resistance formation can no longer be treated with the currently available antibiotics are advancing worldwide. The situation is critical above all in clinics, e.g. in intensive-care units, where antibiotics are administered daily and pathogens can easily develop resistances. Also, the incorrect or excessive use of antibiotics has rapidly increased the number of resistant bacterial strains. Although the problem has previously been solved by using alternative or newly developed antibiotics (e.g. cephalosporins/derivatized antibiotics) and combination therapies (e.g. cotrimoxazole/sulfonamides), new resistances also occur in this case in a relatively short period of time. For example, vancomycin, which was active against certain bacterial strains a short time ago, often can no longer be used in therapy on account of the meanwhile formed resistances. Although major efforts are made to develop new natural antibiotics of different origin from prokaryotes and eukaryotes, only temporary or partial success has been achieved with respect to the rapidly mutating bacterial strains.